Safety device for presses



Patented Oct. 14, 1947 UNITED STATES PATENT OFFICE SAFETY DEVICE FORPRESSES Joseph M. Korkowski, Minneapolis, Minn.

Application September 22, 1943, Serial No. 503,361

15 Claims. 1

This invention relates to improvements safety devices for punch pressesand similar machine tools.

In the ordinary punch press the punch is moved toward and away from thebed or die, usually in a vertical plane, to operate upon the work placedin or on the die, by means of a connection to an overhead crankshaft.Obviously where the work is put in place by hand there is great dangerto the operators fingers and hands from the descending punch. Inoperation, the punch is raised by the crankshaft, drawing the punch upto a top, dead center position and after the work is put in place, thepress is tripped, causing the crankshaft to make one complete revolutionmoving the punch downward against the work and back up to idleposition.

It is customary to provide the press with some form of safety devicesuch as cords which are fastened to the operator's hands and upon whicha pull is exerted, as the punch moves downward, in order to withdraw orretract thehands from the vicinity of the punch and die. However, allsuch safety devices of which I am aware have had the disadvantage thatthe extent of such retraction movement, or the length-to which the cordsare pulled, has been exactly proportional to the distance through whichthe punch moves in its downward or working stroke. In other words, aconsiderable range of travel of the punch in the downward direction hasoccurred before the hands are pulled or retracted from the immediatevicinity of the punch, and it has been noted from actual experience thatthe hands all too frequently are not entirely in the clear before thepunch has reached the work. In the case of careless operators, andparticularly where the nature of the work is such that it projects abovethe die face into the path of the punch, this has resulted in injury toone or more fingers of the hands.

It is the primary object of my invention, therefore, to provide a safetydevice of this nature but wherein the very initial movement of the punchis made effective to accomplish the complete retraction or pulling ofthe hands from the vicinity of the punch, the balance of the movement ofthe punch through its working and return strokes having no furtherretraction effect on the hands. As a result, the operators hands will bewell in the clear before the punch reaches the danger point withreference to the die.

Another object is to provide a safety. device of this character whereinthe cords attached to the operators hands are lightly heldtaut byweights at all times but which are otherwise free to permit the operatorto move them about at will except that, when the punch is traveling nearthe die, the hands cannot reach a dangerous position with respectthereto. Such arrangement further provides that, unless the hands are ina dangerous position, the operation of the safety device will not beapparent to the operator. Thus if the operator withdraws his hands intime, the cords will not jerk or otherwise disturb him, but should hefail to get his hands in the clear the operation of the safety devicewill positively pull the cords to retract the hands.

Another object is to provide a device of the foregoing characteristicswhich is of simple and practical construction and capable of beingreadily applied to the press.

These and other more detailed and specific objects will be disclosed inthe course of the following specification, reference being had to theaccompanying drawings, in which- Fig. 1 is a side view of a punch pressequipped with my safety-device, and showing the positions assumed by theparts when the punch is at its top or idle position.

Fig. 2 is an enlarged fragmentary vertical sectional view through alower part of the safety device, showing the arrangement of the weightsand lower end of the vertical slide member.

Fig. 3 is an elevation of the structure shown in Fig. 2.

Fig. 4 is a horizontal cross section along the line 44 in Fig. 3.

Fig. 5 is an enlarged fragmentary detail View of the gear and rackarrangement, showing the parts in the positions assumed when theretraction movement of the hands is almost completed.

Referring now more particularly and by reference characters to thedrawing, A represents the punch or movable member of a conventional formof punch press B, the punch being supported at its upper end portion bymeans of a bearing C upon the crank D of a crankshaft E. Rotation of thecrankshaft E obviously will cause the upper end pitman-like portion ofthe punch A to travel a circular path and will cause the punch to moveupwardly and downwardly at its lower end toward and away from the die F,or other work, placed upon the bed G of the press.

In practice the punch has a normal idle position wherein it is raised toits fullest from the work and from which, when the press is tripped, thepunch first'moves downwardly on a power or turn stroke. The crankshaft Emakes a complete revolution for each such operation.

My safety device comprises a frame represented generally at l0, which isconveniently and inexpensively fabricated from ordinary piping andcouplings, and which comprises an upper horizontal portion ll secured inany suitable manner at one end 12 to the press B near an upper endthereof. Said upper portion H extends outwardly over the operatorsstation in front of the press. The outer end of the upper frame portionH is then supported by an upright stand member I3 which at a lower endis secured by a flange member I4 to the fioor I5. This stand member maysupport the operator's seat [6 by means of a bracket H, the operatorwhen at work being thus seated between the stand member and the press,and forwardly of the latter.

The upper frame portion Il may, forthe sake of rigidity, comprise a pairof pipes arranged in parallelism and secured by T-couplings 18 to theupper ends of similar parallel pipes forming the upper part of the standmember l3. At the point I9, Fig. l, the double pipe construction may endand by means of elbows 20 and a T-coupling 2! be brought to fit a singlstand pipe 22 as seen in Fig. 3.

A rack member or slide 23 is supported on the upper frame portion 1 I bymeans of suitable slide bearings 24 so that the member may bereciprocated horizontally and lengthwise of the frame portion ll. At theend nearest the press B the rack member 23 is pivoted at 25 to an end ofa drive member or connecting link 26 which comprises a tubular portion21 interiorly tapped to receive a rod 28 which is screwed therein andlocked in position by lock nuts 29. The end of the rod 28 is thenpivotally attached at 30 to the pitman end of the punch A, theconnection being here shown as conveniently made by means of a plate 3|,carrying the pivot 38, secured beneath the screws 32 holding the cap ofthe bearing C in place. The overall length of the drive member 26 mayobviously be adjusted as required to fit the device to a press of anyusual length of stroke and it will be evident that the operation of thepunch will cause the rack member 2-3 to be reciprocated in its bearings24. As the punch A starts its motion from the idle position, as shown inFig. 1, the rack member 23 will be moved outward or forwardly, and asthe crank D travels the first quadrant in its circular path the rackmember will reach its furthermost outward or forward movement. Continuedtravel of the crank D will then begin to pull the rack member 23 backtoward the press and it will of course return to its initial positionwhen the punch reaches idle position again.

The rack member 23 intermediate its ends has a series of gear teeth 33projecting slightly below the lower edge of the member, as clearlyshown, and which cooperate with a partially toothed segment gear 34.Said gear is supported beneath the rack member 23 for oscillationthereby by means of a shaft 35 and suitable bearings 33 secured to. theupper frame portion ll. At each side of its partially toothedcircumference the gear 34 has angularly formed slide surfaces 37 and38..

Mounted on the shaft 35 alongside the segment gear 34, to turntherewith, is a larger segment gear 33 and this gear meshes with anupright rack member 43 having a toothed edge 4! for this purpose. Therack member 43, or slide, is supported for up and down movements withrespect to the stand member [3 of the frame It by means of slidebearings 42 which support the rack member from the side of the standmember facing the press B.

The rack member 43 of course moves in a plane passing alongside thefirst rack member 23, permitting these parts to clear each other.

In the normal position of the parts, with the punch in its raised andidle position, the rack member 23 rests with its teeth 33 just beginningto mesh with the gear 34 and the rack member 40 stands at its highestposition. Now, as the punch starts its operation, the crank D movingover forwardly causes the rack member 23 to be moved outwardly and theengagement of the gear teeth will oscillate or rock the gears 34 and 33in a clockwise direction as viewed in the drawing. This action moves therack member 43 downwardly as will be apparent.

As the motion continues the parts reach the position shown in Fig. 5 andthe various leverages and lengths of the toothed portions of the partsare so selected that this condition occurs before the crank D hastraveled its first quadrant or quarter revolution from top, idleposition. As the crank continues to move the teeth on the rack member 23will then clear the teeth on the gear 34 and as this occurs the slidesurface 31 will have reached about a horizontal position whereat it willslidably engage the underside of the rack member 23 permitting it toslide on in its forward stroke, without turning the gears which are infact locked against further movement at that time by the engagement ofthe slide surface with the rack member.

When the rack member 23 reaches its limit of travel in this directionand reverses its movement, due to the continuation of the crank D in itstravel, the member will slide across the gea 34 until the end tooth 33reengages the teeth on the gear whereupon the gears will be rocked backin the opposite direction, or counterclockwise as shown in the drawing.As the rack member 23 thus reverses the punch A is on its downward orworking stroke but the aforesaid sliding movement of the rack memberbefore reengagement of its teeth 33 with gear 34 maintains the gears 33and 39, and of course the rack member 30, in locked position until thepunch has reached nearly its lower limit of travel.

As the punch then reaches its, lowermost position the gears 3,4 and 39are rocked back to start- 1 positio s. and the rack teeth 33 willfinally clear the teeth of the, gear 34 bringing slide surface. 38 upintoposition for sliding engagement with the rack member 23. as thepunch travels upwardly. When the punch approaches starting positionagain the rack member 23 will be moved back in the opposite directionfinally coming to rest with the teeth 33 again just in mesh with thegear 34 ready to start another cycle of operation.

It will be seen from the foregoing that I provide a connection such thatonly the initial movement of the punch from top idle position operatesthe rack member 40 in the downward d;- rection, whereupon the parts arelocked until the punch reaches the lowermost part of its movement atwhich time the rack member 40 is moved back upwardly to startingposition and locked until ready for the next operation. The reengagementof the rack teeth 33 with the gear 34, after each describeddisengagement, is ensured by the fact that the teeth depend orprojectbelow the lower edge of the rack and thus must engage the end teeth ofthe gear each time. It is, of course, this disengagement andreengagement of the rack member 23 and gear 34 which permits only theseparts of the movements of the former to be used for oscillating thegears, which are useful for my purpose.

. Th downward movement of the rack member 40 is used to draw theoperators hands clear of the press as will now be described. Below thelowermost slide bearing 42 the rack member 45 carries a cross member orcross head 43 to the ends of which upright slid members 44 and 45 aresecured in spaced relation. These slide members 44 and 45 move upwardlyand downwardly within guides 45 and 41 which may be as shown secured toand depended from the lower slide bearing 42 down to a point near thefloor l5. The guides 46 and 41 take the form'of channels of U-shapedcross section (Fig. 4) adapted to nicely receive and guide the slidemembers 44 and 45, and the channels are open on the sides facing thepress B. The inside webs or flanges of the channel shaped guides 46 and41 are cut away from the points 48 (Figs. 2 and 3) up to near theirupper ends in order to clear the cross head 43 as the rack member 40moves up and down.

The slide members 44 and 45 have upright passageways or bores 49 and 50opening through their upper and lower ends and above and in alignmentwith these passageways pulleys 5| and 52 are journaled on the guides 46and 41 by means-of pins 53, said pulleys being located clear of theslide members at their uppermost positions. A cord or flexibleconnecting member is provided for each hand of the operator, and areindicated at 54 and 55. At one end each cord is provided with means forattachment to the hands, such as the straps 56, and at their other endsthe cords 54 and 55 are passed over the respective pulleys 5| and 52 andthence downwardly loosely through the passageways 49 and 50. The lowerends of the cords 54 and 55, below the slide members 44 and 45, aresecured to upper ends of threaded rods 51 and 58 and upon these rodsweights or stops 59 and B ar placed and held from downward displacementby means of nuts BI and 62 threaded on the rods. The upper ends of therods and 58 may freely enter the respective passageways 49 and 50 asclearly shown, and the guides 46 and 41 also act as guides for theweights 59 and 60 to hold the parts in proper alignment forthis'purpose.

In operation, the hands of the operator may be moved toward the pressuntil the pull on the cords 54 and 55 draws the weights 59 and 60 upagainst the lower ends of the slide members 44 and 45. With the rackmember 40 in its normal elevated position the nuts BI and 62 are thenadjusted to the point that the cords will permit the hands to reach thepress for placing the work thereon. Then as the rack member 40 is moveddownwardly, by the press starting its working motion as, previouslydescribed, it will be evident that the slide members 44 and 45 will beardownwardly on the weights 59 and 59, which thus act as stops, and willpull upon the cords to draw or retract the hands away from the press.The hands will be held against return toward the press until the rackmember 45] again moves upwardly, as will 6 the clothing or the like,while the spreading of the cords, provided by the spacing between theslide members 44 and 45, causes the cords to nicely clear the sides ofthe operator seated on the seat It.

By virtue of the constant light tension upon the cords 54 and 55, andtheir running engagement with the slide members 44 and 45, it will alsobe apparent that should the operator withdraw his hands from the pressof his own volition, then the weights 59 and 64 will drop below theslide members and the downward movement of the latter as the press isoperated will have no effect on the cords. Thus, so long as the operatoris careful and keeps his hands in the clear, the safety device will haveno perceptible effect on his hands. But should he negligently start thepress in operation before his hands are clear then the weights, or stopswill necessarily be in position for engagement to pull the cords andforcibly Withdraw the hands.

Attention is directed to the fact that it is the very initial movementof the punch from its uppermost idle position which is used to carry outthe complete retraction movement of the hands. The various gears are soproportioned and arranged'that the first few degrees of movement of thecrank D, less than the first quadrant of its circular path, will rockthe gears to their furthermost position and push the rack member 40 downas far as it goes. Thus the punch will have descended but little beforethe hands are entirely in the clear and the punch cannot have reached adangerous proximity to the hands and work. As seen in Fig. 1 this effectmay be increased by stopping the punch a little short of dead center onits return stroke, for example by a distance indicated at X. Now as thepunch starts each operation it will actually first move upwardly andthen back downwardly while operating the rack member 23 to withdraw thehands and the parts may then be so proportioned that the hands will becompletely in the clear before the punch actually descends below itsidle position as will be understood.

It is understood that suitable modifications may be made in thestructure as disclosed, provided such modifications come within thespirit and scope of the appended claims. Havin now therefore fullyillustrated and described my invention, what I claim to be new anddesireto protect by Letters Patent is:

1. The combination with a punch press having a punch and a pitmanconnected thereto and movable at an upper end in a circular path fro-man upper idle position downwardly through a working stroke and return,of means for withdrawing an operators hands from the vicinity of thelower end of the punch during said working stroke of the punch andpitman, comprising flexible members for attachment to the hands, and amember adapted and arranged to be pushed endwise outwardly from thepress in response to the initial movement of the upper end of the pitmanfrom its idle position through substantially the first quadrant of itscircular path and operative to pull upon the said flexible members andible members for attachment to an operators hands, means for pullingupon said members to pull the hands away from the lower part of thepunch member as it moves downwardly, the said means bein operative inresponse to the movement of the said upper end portion of the pitmantoward its working stroke, and the said pitman being adjusted to stopshort of a top dead center position on its return stroke whereby thesaid means will be operated by the initial travel of the pitman oversaid top dead center position to pull the hands into the clear beforethe punch member has traveled more than a fraction of its downwardworking stroke.

3. A safety device for a punch press havin a punch and a pitmanconnected to the punch and arranged for movement at an upper end in acircular path from an upper idle position downwardly through a workingstroke and upwardly through a return stroke, comprising flexible membersfor connection to the hands of an operator for pulling the hands awayfrom the punch as it descends, means connected between the upper end ofthe pitman and the said flexible members for pulling upon the latter asthe punch descends, and the said means being operative to transmit thesaid pull to the flexible members only during substantially the firstquadrant of the circular path of the pitman from its upper idleposition.

4. A safety device for a punch press having a punch operating pitmanarranged for movement at an upper end in a circular path from an upperidle position downwardly through a working stroke and upwardly through areturn stroke, comprising flexible members for connection to the handsof an operator for pulling the hands away from the punch as it descends,means connected between the upper end of the pitman and the saidflexible members for pulling upon the latter as the punch descends, andthe said means being operative to pull upon the flexible members duringthe first quadrant of the circular path traveled by the pitman as itleaves the upper idle position, to hold said flexible members againstopposite movement until the punch substantially completes its downwardtravel and to release the flexible members for the remaining movement.

5. A safety device for a punch press having a punch and an actuatingpitman arranged for movement at an upper end in a circular path from anupper idle position downwardly through a working stroke and upwardlythrough a return stroke, comprising flexible members for connection tothe hands of an operator for pulling the hands away from the punch as itdescends, means connected between the upper end ofthe pitman and thesaid flexible membersfor pulling upon the latter as the punch descends,and the said means including a gear mechanism, which operatively meshesonly during the initial and latter parts of the working stroke of thepitman.

6. A safety device for a punch press having a punch and a connectedpitman arranged for movement at an upper end in a circular path to movethe punchfrom an upper idle position' downwardly through a workingstroke and upwardly through a return stroke, comprising flexible membersfor connection to the hands of any operator for pulling the hands awayfrom the punch as it descends, means connected between the upper end ofthe pitman and the said flexible members for pulling upon the latter asthe punch descends, and the said means including a gear mechanismoperative to establish a connection to 8 the said flexible members forpulling upon the same only during the first movement of the punch fromidle position and to establish a connection for freeing the flexiblemembers as the punch approaches its lowermost position.

7. A safety device for a punch press having a punchand a pitman arrangedfor movement at an upper end in a circular path to move the punch froman upper idle position downwardly through a working stroke and upwardlythrough a return stroke, comprising flexible members for connection tothe hands of an operator for pulling the hands away from the punch as itdescends, means connected between the upper end of the pitman and thesaid flexible members for pulling upon the latter as the punch descends,and thesaid means including a gear mechanism operative to pull upon theflexible members as the punch moves away from idle position, to lock theflexible members against opposite movement as the punch travels towardthe lower range of its working stroke, and to release the flexiblemembers as the punch reaches its lowermost position.

8, A safety device for a punch press having a punch and a pitmanarranged for movement at an upper end in a circular path to move thepunch from an upper idle position downwardly through a working strokeand upwardly through a return stroke, comprising flexible members forconnection to the hands of an operator for pulling the hands away fromthe punch as it descends, means connected between the upper end of thepitman and the said flexible member for pulling upon the latter as thepunch descends, and the said meansincluding a rack arranged forreciprocation by the upper end of the pitman as it travels its circularpath, a gear for operation by the rack and operatively arranged to pullupon the flexible members as the rack moves in one direction and torelease the members as the rack moves in the opposite direction, andsaid gear being only partially toothed so that only the initialmovements of the rack in the first direction and intermediate part ofthe final movement in the opposite direction will actuate the saidflexible members.

9. A safety device for a punch press having a punch and a pitmanarranged for movement at an upper end in a circular path and to move thepunch from an upper idle position downwardly through a working. strokeand upwardly through a return stroke, comprising flexible members forconnection to. the hands of an operator for pulling the hands away from.the pitman as it descends, means connected between the upper end of the,punch andv the said flexible members for. pulling upon the. latter as,the punch descends, the. said means including a rack arranged forreciprocation by the upper end of. the pitman as it. travels itsvcircular path, a segment gear having a toothed portion adapted to bemoved in one direction by meshing engagement with the rack as itstarts.its movement in response to the travel of the punch from idle position,toward its. working stroke andv to; be moved i-nthe opposite directionby the rack as it returns toward starting position in response to. theapproach of; the. punch to. its lowermost position, the. said toothedportion of the. gear being adapted to move out of meshing engagementwith the rack, between the.

aforesaid movements thereof and the gear having, surfaces for engagementby the rack to lock the gear against movement. except when in mesh withthe rack, and means operative to pull upon and to release the saidflexible members in response to the said opposite movements of the gear.

10. A safety device for punch presses, comprising a rack memberoperatively arranged for reciprocation as the punch travels, a segmentgear meshing with the rack member and adapted to be intermittentlyoscillated thereby, a gear connected to said gear segment, a second rackmember meshing with the gear for reciprocation thereby, and cordsoperatively connected to said second rack member and adapted to bepulled upon and released by the opposite movements thereof, the saidcords being adapted for connection to the hands of an operator forpulling the same from the vicinity of the punch.

11. A safety device for punch presses, comprising a rack memberoperatively arranged for reciprocation as the punch travels, a segmentgear meshing with the rack member and adapted to be intermittentlyoscillated thereby, a gear connected to said gear segment, a second rackmember meshing with the gear for reciprocation thereby, cords adaptedfor connection at one end to the hands of an operator of the press, theother ends of the cords having sliding engagement with the second rackmember, and stop means on said other ends of the cords for engagement bythe said second rack member as it moves in one direction to therebyexert a pull upon the cords for drawing the operators hands away fromthe punch.

12. A safety device for punch presses, comprising a rack memberoperatively arranged for reciprocation thereby as the punch travels, asegment gear meshing with the rack member and adapted to beintermittently oscillated thereby, a gear connected to said gearsegment, a second rack member meshing with the gear for reciprocationthereby, cords adapted for connection at one end to the hands of anoperator of the press, the other ends of the cords having slidingengagement with the second rack member, and stop means on said otherends of the cords for engagement by the said second rack member as itmoves in one direction to thereby exert a pull upon the cords fordrawing the operators hands away from the punch, the said stop means onthe cords being also adapted to act as weights to hold the cords tautbetween the hands and the said prising a member movable in one directionas the punch of the press moves toward the work and movable in theopposite direction as the punch moves away from the work, a pair ofcords adapted at one end for connection to the hands of an operator ofthe press, the said cords being slidably associated with the saidmember, weights on the cords to hold them taut, and the said memberbeing adapted to engage the said weights to exert a pull upon the cordsas it moves in one direction and thereby to pull the hands away from thepunch as it moves toward the work,

14. A safety device of the character described, comprising a membersupported for movement in upward and downward directions, at least oneflexible member adapted at one end for connection to the hand of anoperator and at its other end slidably engaging the said member andhanging therefrom, and a stop member on the hanging end of the flexiblemember adapted for engagement by the lower end of the member as it movesdownwardly to thereby exert a pull upon the end of the flexible memberconnected to the hand.

15. A safety device for punch presses, comprising a member movable inupward and downward directions adjacent to the press, a pair of cordsadapted for connection at one end to the hands of an operator and attheir other ends having stop members for engagement by the said memberas it moves downwardly to thereby pull the hands away from the press,the said ends having free sliding engagement with the said member andthe stop members acting as weights to hold the cords taut, and the saidstop members being adapted to descend as the hands are withdrawn awayfrom the press by the operator and to hang clear of the lowermostposition of the movable member so long as the hands are well clear ofthe press.

JOSEPH M. KORKOWSKI.

REFERENCES CITED 'The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

